Add warmer water. As one of the key ingredients in concrete, water is essential for the curing reaction to occur. The curing time can be hastened by using a slightly warmer water in the mixture as this will encourage the reaction to occur more quickly – do not, however, use blazing hot water as this could be damaging.
For example, if you use slightly warmer water in your concrete mix, you can encourage a quicker reaction and, in turn, a quicker curing time. Avoid water that's too hot or boiling, however, as this will only serve to damage the mix.
Optimum water bath temperatures for accelerated concrete strength development range approximately from 165° to 180°F. The duration of accelerated curing is not critical for the fixed set boiling method.
High temperatures mean faster curing, but fast curing equates to weaker strength in the end. The following study by Paul Klieger in the Portland Cement Association Research Bulletin 103 illustrates this concept. At an age of 1 day the 120°F concrete was strongest and the 25°F concrete was weakest.
Concrete sets much faster on hot weather days, which makes it very difficult to level and finish smoothly before it sets. Your finished slab is more likely to have surface deformities and unevenness in the summer unless precautions are taken.
Upon pouring and throughout curing, the concrete must be kept at 40 degrees if more than 72 inches thick, 45 degrees if 36 to 72 inches thick, 50 degrees if 12 to 36 inches thick, or 55 degrees if less than 12 inches.
Concrete typically takes 24 to 48 hours to dry enough for you to walk or drive on it. However, concrete drying is a continuous and fluid event, and usually reaches its full effective strength after about 28 days.
Retarder can slow the cure of concrete made in the winter mix. For a contractor, Fore-times it is necessary to need slightly water reduce more work time for your surface than what would normally be required. When this is the case, the use of retarder will help to slow the setting of the concrete overlay product.
In cold weather, it may be an advantage to raise the temperature of the fresh concrete at the batching plant so that the concrete retains a sufficient temperature to promote setting and strength development to off-set the risk damage caused by early age freezing.
When concrete is exposed to temperatures above 212° F (the boiling point of water), the moisture in the concrete turns to steam. If the temperature rises more rapidly than the steam can escape through the concrete matrix, the rising pressures exceed the strength of the concrete and it begins to break apart and spall.
The results show a loss of concrete strength with increased maximum heating temperature and with increased initial saturation percentage before firing. For maximum exposure temperatures below 400 °C, the loss in compressive strength was relatively small.
If concrete gets too hot, it may gain strength quickly, but the final strength will be less than ideal. If concrete stays cold, it won't set, and work on the concrete is stalled. Curing between the ideal temperatures of 50 to 90 degrees results in the best combination of final strength versus time to cure.
Hot weather can have significant impacts to the long-term strength of your concrete. Yes, the initial strength will be stronger with faster than usual set times, but it does not give enough time for the crystals surrounding the aggregate to grow and reach the max strength.
If water evaporates too quickly, it will weaken the finished product with stresses and cracking. To put it simply, the goal is to keep the concrete saturated during the first 28 days. The first 7 days after installation you should spray the slab with water 5-10 times per day, or as often as possible.
Moist curing is a common method of concrete curing. It involves wetting the concrete slab often with water (5-7 times per day) for the first 7 days. This method ensures your concrete slab will be extremely strong and durable, because it allows the moisture to evaporate slowly, preventing cracks and shrinks.
Spray: To maintain the proper moisture levels, concrete should be sprayed with water frequently. This is known as moist-curing. Most specialists recommend watering the slab 5 to 10 times per day for the first seven days. Moist-cured concrete can be up to 50% stronger than dry-cured concrete.
If the rain begins after 2-4 hours from concrete placement, the surface needs to be covered; otherwise, the concrete surface will suffer damages. If rains pound on concrete 12 hours after placement, the likeliness of any damage is negligible.
Once the concrete has been finished (between 4-8 hours after pouring) and has set hard enough for walking on, the effects of rain should be minimal. The curing process is a chemical reaction, with ready mix concrete taking up to 28 days to fully cure.
If you had time to complete the finishing process and the concrete has stiffened (typically 4 to 8 hours after mixing), rainwater may cause little if any damage. In fact, once concrete sets, water on the surface is actually beneficial because it aids in hydration and curing.
The Australian Standard 1379: Specification and Supply of Concrete stipulates that concrete temperatures should be between 5°C and 35°C at the point of delivery.
Prevent excess water.
High water content in a concrete mix design is one of the primary causes of differential volume changes that cause high shrinkage and excessive cracking. The use of chemical admixtures, such as water reducers, creates easy-to-place, high slump concrete, without adding excess water.
Pouring concrete over existing concrete is possible as long as you do so properly. When the old concrete serves as the foundation for your new pour, it needs to be a solid one.
To put it simply, the answer is yes. Warm temperatures cause cement to set faster, and the faster cement sets, the faster it begins to cure.